class Wall:
    @classmethod
    def get_id(cls):
        return '#'

def find_class(attr,sign):
    classes=[]
    for i in globals():
        if type(eval(i)) == type:
            classes.append(i)
    for i in classes:
        if attr in eval(i).__dict__:
            source=eval(f'{i}.{attr}()')
            if source == sign:
                return i

print(find_class('get_id','#'))
